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Wondering if anyone has ever had to shim the brass nut for the 'cross-slide?' to work right? I've tried the original and a new one. Both leave it harder to turn the closer the cross-slide gets to the turning lever. Any idea's would be appreciated as i would like to get this done and together and use it some.
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Before getting involved with shims, first loosen off the rear gib adjusting screw and see if that makes any difference. If not, try loosening the two bolts which secure the bracket that carries the cross-slide feedscrew. Just loosen them enough to allow the bracket to move around as far as the wriggle room in the bolt holes permits. Then wind the slide out as far as it will come, and tighten up the bolts. This might cure the problem if the hole through the bracket was a bit out of line with the brass nut. In that case, the slide would move easily when well back, but get progressivly stiffer as the nut approached the bracket and tried to bend the feedscrew more and more to accommodate the misalignment.
I had a similar problem on my lathe, but it had a different cause. Due to poor manufacture, the top of the male dovetail on the saddle fouled the roof of the female dovetail in the slide when I tried to wind the slide fully out towards me. Once tracked down with by probing around with a 5 thou feeler gauge, the problem was soom solves with a few strokes of a file to give the necessay clearance.
Andy
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--- In 7x12minilathe@..., "G." wrote:
Wondering if anyone has ever had to shim the brass nut for the 'cross-slide?' to work right? I've tried the original and a new one. Both leave it harder to turn the closer the cross-slide gets to the turning lever. Any idea's would be appreciated as i would like to get this done and together and use it some.
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There is a pdf file with photos on the group web site of how to modify the cross slide nut and make it easier to adjust. I did the modification years ago and it makes adjusting easy. I also lapped the gibs.
If you can't find the file "Cross Slide Nut Modification" E-mail me separately and I will send it to you.
John
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It's already got adjusting screws!
They do tend to unadjust themselves, mostly from the screws vibrating loose. Some folks have shimmed them to eliminate the problem.
Roy
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--- In 7x12minilathe@..., "G." wrote:
Wondering if anyone has ever had to shim the brass nut for the 'cross-slide?' to work right? I've tried the original and a new one. Both leave it harder to turn the closer the cross-slide gets to the turning lever. Any idea's would be appreciated as i would like to get this done and together and use it some.
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Roy, that's why the modification to the brass nut is necessary. Its easy, just follow the article and it helps the adjustment stay.
John
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On Sun, Feb 10, 2013 at 4:19 PM, Roy <roylowenthal@...> wrote:
?
It's already got adjusting screws!
They do tend to unadjust themselves, mostly from the screws vibrating loose. Some folks have shimmed them to eliminate the problem.
Roy
--- In 7x12minilathe@..., "G." wrote:
>
> Wondering if anyone has ever had to shim the brass nut for the 'cross-slide?' to work right? I've tried the original and a new one. Both leave it harder to turn the closer the cross-slide gets to the turning lever. Any idea's would be appreciated as i would like to get this done and together and use it some.
>
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The nut's vertical position can be adjusted to match the CS leadscrew using the procedure given on page 13 of this LMS manual:
< >
This should eliminate the binding you're experiencing.
You can also tip the nut (using the adjustments provided) to reduce backlash due to the nut, as described in that procedure.
Note that backlash is the sum from this nut, and the space between the shoulder on the leadscrew and the pocket containing the shoulder. You can add a shim to minimize backlash due to a poor fit here. Alternatively, adding a ball bearing to the CS leadscrew can eliminate need for the pocket, leaving just backlash from the nut.
To answer your question, I shimmed the CS lead nut on my machine after adding a ball bearing. I found tipping the nut reduces backlash temporarily but the nut then wears fairly rapidly until backlash gets back to about 5 thou where it sort of stabilizes and wears much slower. Bottom line: modest backlash is something you'll get used to and take up without conscious effort.
John
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--- In 7x12minilathe@..., "G." wrote:
Wondering if anyone has ever had to shim the brass nut for the 'cross-slide?' to work right? I've tried the original and a new one. Both leave it harder to turn the closer the cross-slide gets to the turning lever. Any idea's would be appreciated as i would like to get this done and together and use it some.
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Andy Franks in reply to this recent post.
Do different mini lathe (Chinese manufacturers)?opt for brass and or cast iron cross feed nuts.? Does cast iron have physical self lubricating properties (graphite) and would phosphor bronze have even been a better choice of material ? My ?Real Bull lathe was?originally?fitted with a cast iron nut. As you remember opted with the cross feed mods I did to put in double nuts (only to stop the screw running off the nut when I did the extended the travel change) and made 2 new nuts in brass so one of the nuts is always in contact with the screw at the end of travel towards the splash guard. Naturally re positioned them on the cross slide,backlash and or slop now is not an issue. I think double nuts helps in some of the gib issues we all seem to have,being that the screw is better supported. Again,many thanks for the loan off your LH Tap you made, it worked very well. Still have to
make my own tap ,it's a round to it job. But thinking now I should of used cast iron , although brass the has never been a problem. Best to leave alone at this moment. Regards John L
From: andyf1108
To: 7x12minilathe@...
Sent: Monday, February 11, 2013 12:57 AM
Subject: [7x12minilathe] Re: brass nut alignment?
?
Before getting involved with shims, first loosen off the rear gib adjusting screw and see if that makes any difference. If not, try loosening the two bolts which secure the bracket that carries the cross-slide feedscrew. Just loosen them enough to allow the bracket to move around as far as the wriggle room in the bolt holes permits. Then wind the slide out as far as it will come, and tighten up the bolts. This might cure the problem if the hole through the bracket was a bit out of line with the brass nut. In that case, the slide would move easily when well back, but get progressivly stiffer as the nut approached the bracket and tried to bend the feedscrew more and more to accommodate the misalignment.
I had a similar problem on my lathe, but it had a different cause. Due to poor manufacture, the top of the male dovetail on the saddle fouled the roof of the female dovetail in the slide when I tried to wind the slide fully out towards me. Once tracked down with by probing around with a 5 thou feeler gauge, the problem was soom solves with a few strokes of a file to give the necessay clearance.
Andy
--- In 7x12minilathe@..., "G." wrote:
>
> Wondering if anyone has ever had to shim the brass nut for the 'cross-slide?' to work right? I've tried the original and a new one. Both leave it harder to turn the closer the cross-slide gets to the turning lever. Any idea's would be appreciated as i would like to get this done and together and use it some.
>
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I don't know, John.
I can produce no authority for this, but I imagine that bronze might be the best material for feedscrew nuts. Mine was originally cast iron, but as a result of certain "unintended consequences" of remachining my saddle dovetail I replaced it with one of the brass ones you kindly made and included when returning the tap, and that works just fine.
But if bronze is good for feedscrews, why not bronze half nuts on leadscrews?
Returning to G's original query, it has been suggested that he uses the adjustment which reduces backlash by rocking the feedscrew nut slightly. If his cross slide was stiff throughout its travel, that might help, but it only stiffens up at the outward end. That makes me think the cause probably lies elsewhere; hence the suggestions I put forward earlier.
Andy
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--- In 7x12minilathe@..., John Lindo wrote:
Andy Franks in reply to this recent post.
Do different mini lathe (Chinese manufacturers)??opt for brass and or cast iron cross feed nuts.?
Does cast iron have physical self lubricating properties (graphite) and would phosphor bronze have even been a better choice of material ?
My ??Real Bull lathe was??originally??fitted with a cast iron nut.
As you remember opted with the cross feed mods I did to put in double nuts (only to stop the screw
running off the nut when I did the extended the travel change) and made 2 new nuts in brass so
one of the nuts is always in contact with the screw at the end of travel towards the splash guard.
Naturally re positioned them on the cross slide,backlash and or slop now is not an issue.
I think double nuts helps in some of the gib issues we all seem to have,being that the screw is better supported.
Again,many thanks for the loan off your LH Tap you made, it worked very well.
Still have to make my own tap ,it's a round to it job.
But thinking now I should of used cast iron , although brass the has never been a problem.
Best to leave alone at this moment.
Regards
John L
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The primary adjustment is to set the centre adjuster up, with the nut close
up to the handle. Feel for the middle of the range of adjustment at that
point, then work on balancing the two outer adjusters one against the other,
so slack is taken up, but it handle still turns freely throughout the thread
length.
The centre adjuster sets the nuts overall height, the two outer ones balance
or push one against the other, to take up slack in the thread. If you then
measure the thickness of the shim required, just under the centre it makes
the whole process simpler in the future as well as making the nut more
stable. Instead of adjusting the centre, then you just tighten it up against
the shim.
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-----Original Message-----
From: 7x12minilathe@... [mailto:7x12minilathe@...]
On Behalf Of G.
Sent: 10 February 2013 22:27
To: 7x12minilathe@...
Subject: [7x12minilathe] brass nut alignment?
Wondering if anyone has ever had to shim the brass nut for the
'cross-slide?' to work right? I've tried the original and a new one. Both
leave it harder to turn the closer the cross-slide gets to the turning
lever. Any idea's would be appreciated as i would like to get this done and
together and use it some.
------------------------------------
Yahoo! Groups Links
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Hi John, Andy
I agreee with Andy the bronze would be the best material by some margin with brass a little better than cast iron but as with much selection in low cost equipment material cost is often a key driver. A quick look through my favoured model engineering supplier for suitable size section gave brass as just over twice the price of cast iron and bronze just over three times.
Cast iron is actually a quite reasonable bearing material for low speed plain bearings due to the graphite content and in conjunction with steel quite hard wearing.
My Real Bull lathe is nearly 10yo and came with cast iron nuts and is still going strong with little wear to nut or screw.
The "rocking nut" arrangement works by reducing the clearance at the end but then concentrates the load leading to faster wear in use, A higher precision nut and screw orf better materials would be a better soultion but cost then is the issue. Lead screw half nuts is likely a cost issue again.
Gerry W
Leeds UK
To: 7x12minilathe@... From: andyf.1108@... Date: Mon, 11 Feb 2013 11:20:05 +0000 Subject: [7x12minilathe] Re: brass nut alignment?
?
I don't know, John.
I can produce no authority for this, but I imagine that bronze might be the best material for feedscrew nuts. Mine was originally cast iron, but as a result of certain "unintended consequences" of remachining my saddle dovetail I replaced it with one of the brass ones you kindly made and included when returning the tap, and that works just fine.
But if bronze is good for feedscrews, why not bronze half nuts on leadscrews?
Returning to G's original query, it has been suggested that he uses the adjustment which reduces backlash by rocking the feedscrew nut slightly. If his cross slide was stiff throughout its travel, that might help, but it only stiffens up at the outward end. That makes me think the cause probably lies elsewhere; hence the suggestions I put forward earlier.
Andy
--- In 7x12minilathe@..., John Lindo wrote:
>
> Andy Franks in reply to this recent post.
>
> Do different mini lathe (Chinese manufacturers)??opt for brass and or cast iron cross feed nuts.?
> Does cast iron have physical self lubricating properties (graphite) and would phosphor bronze have even been a better choice of material ?
> My ??Real Bull lathe was??originally??fitted with a cast iron nut.
> As you remember opted with the cross feed mods I did to put in double nuts (only to stop the screw
> running off the nut when I did the extended the travel change) and made 2 new nuts in brass so
> one of the nuts is always in contact with the screw at the end of travel towards the splash guard.
> Naturally re positioned them on the cross slide,backlash and or slop now is not an issue.
> I think double nuts helps in some of the gib issues we all seem to have,being that the screw is better supported.
> Again,many thanks for the loan off your LH Tap you made, it worked very well.
> Still have to make my own tap ,it's a round to it job.
> But thinking now I should of used cast iron , although brass the has never been a problem.
> Best to leave alone at this moment.
> Regards
> John L
>
>
>
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An interesting experiment would be an acetal nut. Possibly someone could try it and let the group know how it worked out...
Perhaps make a round acetal nut as described in the link below, plus a steel adapter with shape similar to the original nut but a large through hole. Turn the completed acetal nut down to fit into the adapter, press it in, then lock in place with set screws or pins. Or, the screws that hold the adapter to the CS could lock the nut in place.
< >
Based on reports from those who tried it, it works well, has little to no backlash, and doesn't wear rapidly. So far it has been used on Acme threads - the 7x12 thread would be exploring new territory.
John
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--- In 7x12minilathe@..., gerry waclawiak wrote:
Hi John, Andy
I agreee with Andy the bronze would be the best material by some margin with brass a little better than cast iron but as with much selection in low cost equipment material cost is often a key driver. A quick look through my favoured model engineering supplier for suitable size section gave brass as just over twice the price of cast iron and bronze just over three times.
Cast iron is actually a quite reasonable bearing material for low speed plain bearings due to the graphite content and in conjunction with steel quite hard wearing.
My Real Bull lathe is nearly 10yo and came with cast iron nuts and is still going strong with little wear to nut or screw.
The "rocking nut" arrangement works by reducing the clearance at the end but then concentrates the load leading to faster wear in use, A higher precision nut and screw orf better materials would be a better soultion but cost then is the issue. Lead screw half nuts is likely a cost issue again.
Gerry W
Leeds UK
To: 7x12minilathe@...
From: andyf.1108@...
Date: Mon, 11 Feb 2013 11:20:05 +0000
Subject: [7x12minilathe] Re: brass nut alignment?
I don't know, John.
I can produce no authority for this, but I imagine that bronze might be the best material for feedscrew nuts. Mine was originally cast iron, but as a result of certain "unintended consequences" of remachining my saddle dovetail I replaced it with one of the brass ones you kindly made and included when returning the tap, and that works just fine.
But if bronze is good for feedscrews, why not bronze half nuts on leadscrews?
Returning to G's original query, it has been suggested that he uses the adjustment which reduces backlash by rocking the feedscrew nut slightly. If his cross slide was stiff throughout its travel, that might help, but it only stiffens up at the outward end. That makes me think the cause probably lies elsewhere; hence the suggestions I put forward earlier.
Andy
--- In 7x12minilathe@..., John Lindo wrote:
Andy Franks in reply to this recent post. Do different mini lathe (Chinese manufacturers)? opt for brass and or cast iron cross feed nuts.? Does cast iron have physical self lubricating properties (graphite) and would phosphor bronze have even been a better choice of material ? My ? Real Bull lathe was? originally? fitted with a cast iron nut. As you remember opted with the cross feed mods I did to put in double nuts (only to stop the screw running off the nut when I did the extended the travel change) and made 2 new nuts in brass so one of the nuts is always in contact with the screw at the end of travel towards the splash guard. Naturally re positioned them on the cross slide,backlash and or slop now is not an issue. I think double nuts helps in some of the gib issues we all seem to have,being that the screw is better supported. Again,many thanks for the loan off your LH Tap you made, it worked very well. Still have to make my own tap ,it's a round to it job. But thinking now I should of used cast iron , although brass the has never been a problem. Best to leave alone at this moment. Regards John L
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On 02/11/2013 03:20 AM, andyf1108 wrote: I don't know, John.
I can produce no authority for this, but I imagine that bronze might be the best material for feedscrew nuts. Mine was originally cast iron, but as a result of certain "unintended consequences" of remachining my saddle dovetail I replaced it with one of the brass ones you kindly made and included when returning the tap, and that works just fine.
But if bronze is good for feedscrews, why not bronze half nuts on leadscrews?
Returning to G's original query, it has been suggested that he uses the adjustment which reduces backlash by rocking the feedscrew nut slightly. If his cross slide was stiff throughout its travel, that might help, but it only stiffens up at the outward end. That makes me think the cause probably lies elsewhere; hence the suggestions I put forward earlier.
Andy
I haven't looked at that nut in a long time (since I drilled the recess into it so it seats better) but is there room to put in a DIY acetyl nut? The type you form to your particular leadscrew? -- Jerry Durand, Durand Interstellar, Inc. www.interstellar.com tel: +1 408 356-3886, USA toll free: 1 866 356-3886 Skype: jerrydurand
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Interesting idea, John. I haven't followed your link, but suspect it's one I've seen before, heating the screw while compressing the acetal on to it in a vice (or vise). Should work even better with an M10 thread, where only a small amount of acetal needs?to be displaced.
?
Now, if there was a?way to take out any backlash which?developed in service by squeezing?opposite sides of your steel adapter and thus the acetal nut inside it.....?? But there probably isn't room for such refinements.
?
Andy
?
?
To: 7x12minilathe@... From: John@... Date: Mon, 11 Feb 2013 15:23:59 +0000 Subject: [7x12minilathe] Re: brass nut alignment? ?
An interesting experiment would be an acetal nut. Possibly someone could try it and let the group know how it worked out...
Perhaps make a round acetal nut as described in the link below, plus a steel adapter with shape similar to the original nut but a large through hole. Turn the completed acetal nut down to fit into the adapter, press it in, then lock in place with set screws or pins. Or, the screws that hold the adapter to the CS could lock the nut in place.
< >
Based on reports from those who tried it, it works well, has little to no backlash, and doesn't wear rapidly. So far it has been used on Acme threads - the 7x12 thread would be exploring new territory.
John
toggle quoted message
Show quoted text
--- In 7x12minilathe@..., gerry waclawiak wrote: > > Hi John, Andy > > I agreee with Andy the bronze would be the best material by some margin with brass a little better than cast iron but as with much selection in low cost equipment material cost is often a key driver. A quick look through my favoured model engineering supplier for suitable size section gave brass as just over twice the price of cast iron and bronze just over three times. > > Cast iron is actually a quite reasonable bearing material for low speed plain bearings due to the graphite content and in conjunction with steel quite hard wearing. > > My Real Bull lathe is nearly 10yo and came with cast iron nuts and is still going strong with little wear to nut or screw. > > The "rocking nut" arrangement works by reducing the clearance at the end but then concentrates the load leading to faster wear in use, A higher precision nut and screw orf better materials would be a better soultion but cost then is the issue. Lead screw half nuts is likely a cost issue again. > > Gerry W > Leeds UK > > To: 7x12minilathe@...> From: andyf.1108@... > Date: Mon, 11 Feb 2013 11:20:05 +0000 > Subject: [7x12minilathe] Re: brass nut alignment? > > > > > > > > > > > > > > > > > > > > > > > > > > > I don't know, John. > > > > I can produce no authority for this, but I imagine that bronze might be the best material for feedscrew nuts. Mine was originally cast iron, but as a result of certain "unintended consequences" of remachining my saddle dovetail I replaced it with one of the brass ones you kindly made and included when returning the tap, and that works just fine. > > > > But if bronze is good for feedscrews, why not bronze half nuts on leadscrews? > > > > Returning to G's original query, it has been suggested that he uses the adjustment which reduces backlash by rocking the feedscrew nut slightly. If his cross slide was stiff throughout its travel, that might help, but it only stiffens up at the outward end. That makes me think the cause probably lies elsewhere; hence the suggestions I put forward earlier. > > > > Andy > > > > --- In 7x12minilathe@..., John Lindo wrote: > > > > > > Andy Franks in reply to this recent post. > > > > > > Do different mini lathe (Chinese manufacturers)? opt for brass and or cast iron cross feed nuts.? > > > Does cast iron have physical self lubricating properties (graphite) and would phosphor bronze have even been a better choice of material ? > > > My ? Real Bull lathe was? originally? fitted with a cast iron nut. > > > As you remember opted with the cross feed mods I did to put in double nuts (only to stop the screw > > > running off the nut when I did the extended the travel change) and made 2 new nuts in brass so > > > one of the nuts is always in contact with the screw at the end of travel towards the splash guard. > > > Naturally re positioned them on the cross slide,backlash and or slop now is not an issue. > > > I think double nuts helps in some of the gib issues we all seem to have,being that the screw is better supported. > > > Again,many thanks for the loan off your LH Tap you made, it worked very well. > > > Still have to make my own tap ,it's a round to it job. > > > But thinking now I should of used cast iron , although brass the has never been a problem. > > > Best to leave alone at this moment. > > > Regards > > > John L > > > > > > > > > >
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John Mattis
GadgetBuilder
gerry waclawiak